package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.ObjectUtil;
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.conditions.query.QueryChainWrapper;
import com.hmdp.dto.Result;
import com.hmdp.dto.UserDTO;
import com.hmdp.entity.Follow;
import com.hmdp.mapper.FollowMapper;
import com.hmdp.service.IFollowService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.service.IUserService;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.UserHolder;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class FollowServiceImpl extends ServiceImpl<FollowMapper, Follow> implements IFollowService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private IUserService userService;

    /**
     * 关注和取关
     * @param followUserId
     * @param isFollow
     * @return
     */
    @Override
    public Result follow(Long followUserId, boolean isFollow) {

        //获取登录的用户id
        Long userId = UserHolder.getUser().getId();

        String key = "follow:" +userId;
        Follow follow = new Follow();
        //1.判断是要关注还是取关
        if (isFollow){
            //2.关注,新增数据到数据库
            follow.setFollowUserId(followUserId);
            follow.setUserId(userId);
            boolean isSuccess = save(follow);
            if (isSuccess){
                //把关注的用户id,放入redis的set集合
                stringRedisTemplate.opsForSet().add(key,followUserId.toString());
            }
        }

        else {
            //3.取关,删除数据  delete from tb_follow where userId = ? and follow_user_id = ?
            boolean isRemove = remove(
                    new LambdaQueryWrapper<Follow>()
                            .eq(Follow::getUserId,userId)
                            .eq(Follow::getFollowUserId,followUserId)
            );
            if (isRemove){
                //把关注的用户id从Redis的set集合中移除
                stringRedisTemplate.opsForSet().remove(key,followUserId.toString());
            }
        }
        return Result.ok();
    }

    /**
     * 根据id查询是否关注
     * @param followUserId
     * @return
     */
    @Override
    public Result isFollow(Long followUserId) {
        //获取登录的用户id
        Long userId = UserHolder.getUser().getId();
        //查询是否关注 select count(*) from tb_follow where userId = ? and follow_user_id = ?
        Long count = lambdaQuery().eq(Follow::getUserId, userId).eq(Follow::getFollowUserId, followUserId).count();
        //判断(由于Long=是个包装类,可以为null,可能会报空指针错误,所以这里判断是不是为null,如果是null则赋值0)
        count = ObjectUtil.defaultIfNull(count, 0L);
        return Result.ok(count > 0);
    }

    /**
     * 查询共同关注
     * @param id
     * @return
     */
    @Override
    public Result followCommons(Long id) {
        //查询当前登录的用户
        Long userId = UserHolder.getUser().getId();
        String key = "follow:" +userId;
        //求交集
        String key2 = "follow:" +id;
        Set<String> intersect = stringRedisTemplate.opsForSet().intersect(key, key2);
        if (intersect == null || intersect.isEmpty()){
            //无交集,返回空集合
            return Result.ok(Collections.emptyList());
        }
        //解析集合(String转Long)
        List<Long> ids = intersect.stream().map(Long::valueOf).collect(Collectors.toList());
        /*List<UserDTO> users = userService.listByIds(ids).stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());*/

        List<UserDTO> users = BeanUtil.copyToList(userService.listByIds(ids), UserDTO.class);
        return Result.ok(users);
    }
}
